1. Field of the Invention
The present invention also relates to a device for conveying and preparing a belt construction strip for constructing a belt of a pneumatic vehicle tire with parallel reinforcing members, e.g., steel members, positioned to extend diagonally to the feed direction, and embedded in the belt construction material, e.g., rubber, for processing in a subsequent processing device, e.g., a belt construction drum. Two continuous conveying devices may be successively positioned, i.e., one after the other, in a feed direction, and at least the conveying device disposed upstream relative to the feed direction may be laterally movable in a controlled manner.
2. Discussion of the Background Information
It is known to form belt construction strips for constructing a belt of a pneumatic vehicle tire out of parallel steel cords embedded in rubber, positioned to extend diagonally to a feed direction, and to transport them to a belt construction drum via continuous conveyor belts. The front end of the belt construction strip supplied to the belt construction drum may be placed on the drum, the belt construction drum is rotated around its axis, and the belt construction strip is wound once around the circumference of the belt construction drum so that the rear edge of the wound belt construction strip on the drum comes into contact with the front edge of the belt construction strip. The two ends of the belt construction strip are spliced to each other along their front and rear edges, respectively, without the steel cords overlapping. A second or additional belt layer is usually mounted onto the first belt layer in the same manner. In order for the steel cords, which are given the desired alignment in the pneumatic vehicle tire with an acute angle between 10° and 30° relative to an equatorial plane in radial pneumatic vehicle tires with radial casings, the belt construction strips are formed so that in the laying, the steel cords already assume an acute angle, for example of 10 to 30°, relative to the circumference direction.
In order not to jeopardize the functionality of a pneumatic vehicle tire, the steel cords are prevented, to the greatest extent possible, from being discontinuous in the axial span of the belt. Therefore, when being laid, the front end and the rear end of the belt construction strip must also be formed to be substantially parallel to the alignment of the steel cords and, consequently, must be formed to enclose the acute angle relative to the circumference direction. Therefore, the belt construction strips are formed with lateral and substantially parallel side edges, a diagonally extending front edge, and a diagonally extending rear edge, respectively, so that a substantially triangular front tip, formed between the front edge and one side edge, encloses an acute angle, adjoining an substantially rectangular main part laterally defined by the two side edges. The main part adjoins a substantially triangular rear tip, formed between the rear edge and the other side edge, enclosing an acute angle. This construction strip is normally conveyed to the belt construction drum with its front tip first.
For manufacturing reasons, as well as due to other force influences during the conveying, the side edges of the belt construction strip, which is comprised of rubber and steel cord, are generally not precisely straight in the course of their edges, but are curvilinear. Curvilinearity of the two side edges can be formed as different to each other so that a central symmetry line running in the feed direction, i.e., between the side edges, represents a curvilinear curve running between the two side edges.
Furthermore, generally the two tips are also frequently curved in an irregular fashion due to different external force effects and due to the plastic deformability of the material. The tips can be formed as curved both axially inward and axially outward, or even curved in a directionally changing manner.
The belt construction strips are usually manufactured from a continuous belt construction band by cutting, parallel to the diagonally extending steel cords, to form the rear edge of a previous belt construction strip and a front edge of a next (subsequent) belt construction strip. Through the cutting motion of the knife from the one side edge to the other side edge, rubber material is pulled along to the side with the knife so that the front and rear tips can be curved. This curvature, however, can also be produced by other external force effects during the production of the belt construction strip or during the conveying to the belt construction drum, e.g., due to mechanical contact, side edge stops or front edge stops are a danger source for the production of this kind of curvatures.
When laying a belt construction strip of this kind, irregularities in the contour course of the side edges, as well as the curvatures in the area of the front and rear tips, lead to the fact that the front ends to be spliced can be axially offset relative to each other, and that there is no parallel, touching contour course then between the front edge and rear edge, by which the production of a reliable splicing weld can be hindered and, in the extreme case, prevented.
The irregular, unevenly curved course of the two side edges relative to each other, and the symmetry axis produced by this, which is formed running in a curved fashion between the side edges, brings about the fact that, over the circumference of the tire, the belt construction strip is also given an irregular axial extension and positioning. This jeopardizes the driving properties, the uniformity, and the functionality of a pneumatic vehicle tire produced in this way.
DE 39 13 240 C2 has disclosed using lateral guide rolls, which are positioned on both sides of the metal cord strip and can be jointly adjusted in the axial direction, to straighten a metal cord strip in the course of its side edges. The metal cord strip is cut on a diagonal on the ends and is utilized for the manufacture of a pneumatic vehicle tire. The metal cord strip is conveyed past the lateral stops formed by the lateral guide rolls and is laterally pressed to a desired width. In this manner, the side edges are in fact straightened, but this causes them to be formed to be irregularly thick because only the rubber material in the strip edge region, which reaches axially outward beyond the limit edge formed by the lateral guide rolls, is pressed inward toward the strip. Thus, the rubber material moves out of the way either upward or downward. The previous uneven and mutually irregular contour courses of the two side edges lead to irregular thickness courses of the side edges. Thus, the thickness courses are unevenly irregular relative to each other. Consequently, not only are irregularities of the thickness course formed in both sides of the finished pneumatic vehicle tire, but the two irregular thickness courses are formed as being unevenly irregular so that in a wide variety of circumferential positions on the pneumatic vehicle tire, different maximal thicknesses are produced on the respective sides. Consequently, the uniformity of the tire is impaired. The desired width format that the strip should assume is adjusted by the lateral guide rolls, which can only be adjusted together with each other. As a result, the kind of irregularities in the contour course that protrude beyond the adjusted side position of the guide rolls are actually straightened.
Irregularities in the side edge course, which do not reach the lateral position of the guide rolls, are not altered. As a result of this, irregular curvature courses of both side edges can remain. Thus, the uniformity, the driving properties, and the functionality of the vehicle tire can be further impaired. For the processing of the tips of the metal cord strip, magnets that can be laterally pivoted are guided toward the tips and are intended to pull the steel cords in the metal cord strips against a lateral mechanical stop. Provided that the tips are actually pulled all the way to the stops, then the tips should be aligned there with their side edges against the stops. This also produces the alignment, provided that it succeeds, merely by squeezing together the side edges and accepting an increase in material thickness. This device requires very strong magnets to pull the tips, particularly the tips of belt construction strips with very tough rubber material, toward the stops in a truly reliable manner. In this manner, a tip of the metal cord strip, which is curved axially inward, may actually be pulled by very strong magnets in an axially outward direction to such a degree that the side edge is straightened in the region of the tip. The material pressed away by the stop primarily leads to a thickening of the belt material in the region of the side edge of the metal cord strip. The curved tip is only slightly curved and remains substantially curved in its front and rear edge courses, respectively. With this alignment, there is great danger that the front and rear edge of the metal cord strip still assume a perceptibly curved, non-parallel course after being laid on a belt construction drum. This jeopardizes a reliable splice. Only with very strong magnets and with some less tough types of rubber with very flexible steel cords, is it possible to ensure that the front and rear edges are effectively pulled against the lateral stops and to ensure at least an axial agreement of the position of the front and rear edges on the belt construction drum. When the type of rubber for the belt construction strip is changed, there is always a consequent danger that the alignment force of the magnets will not be ensured. If a changeover to correspondingly strong magnets is forgotten, then the quality of the pneumatic vehicle tire is jeopardized.
On the whole, the device described by DE 39 13 240 C2, which is for aligning a metal cord strip, is very costly in its mechanical construction. A large number of components, lateral guide rolls, mechanisms for adjusting the lateral guide rolls, mechanical stops, levers, and laterally pivotable magnets are required, which necessitate a high expenditure for manufacture and maintenance, for example, of the large number of different joints. The large number of components brings with it a large number of malfunction sources. The effect of the large number of mechanical components, such as a number of lateral guide rolls and lateral stops, furthermore brings with it the danger that due to friction effects between the laterally acting mechanical elements and the metal cord strip, additional, undesirable deformations of the metal cord strip are produced.
U.S. Pat. No. 4,769,104 has disclosed squeezing a belt construction strip on a conveyor belt by two mechanical, lateral aligning rails that are moved toward each other, to straighten the side edges. Here, too, the purely laterally acting mechanical force cause a straightening of the side edge, along with a shifting of material at the expense of irregular thickness changes in the region of the side edge. The lateral alignment rails are moved toward each other until they reach a particular spacing, e.g., laterally inward-directed bulges, which reach axially inward toward the strip beyond this position of the lateral alignment rails and do not touch them, are not aligned. Therefore, even with an alignment using a device according to U.S. Pat. No. 4,769,104, unevenly shaped irregularities of the side edge courses of the two side edges relative to each other remain and, consequently, curvilinear symmetry axes also remain. To align the tips of the belt construction strip, a first mechanical pivoting lever is swiveled, which is pivoted from the outside of the side edge toward the front-most tip of the side edge. The first mechanical pivoting lever only contacts the tip in the front end region of the tip. The arm presses the front end of the tip axially inward in order to align the side edge in the tip. Then, the first mechanical pivoting lever is pivoted away from the side edge. A second mechanical arm, which extends over an entire width of the belt construction strip, is pivoted toward the front edge and is utilized to straighten the front edge by virtue of the fact that, with further pivoting, it presses against the front edge like a mechanical stop. The rubber material along the front edge and where the material is worked in the edge region is compressed and the front-most end of the tip of the belt construction strip is pressed axially outward once more so that it can once again leave the position halfway aligned by the first lever. The side edge in the tip region, which has only been pressed inward by the virtual point contact of the first lever against the front-most tip end for alignment, is otherwise not aligned in its course, even before the pivoting of the second lever. The actuation of the second arm produces slightly more curving, wherein as shown, it also runs the risk with its front end of the tip, of completely losing the alignment. Moreover, the front edge is straightened somewhat reliably by the second lever only if the pivoting lever acts as uniformly as possible, i.e. in the same alignment on the front edge. Due to the lever action of the pivoting lever, the force effects over the length of the front edge, though, vary as a function of the distance to the pivoting lever axis. Since the pivoting lever is intended to slightly compress the front edge material for alignment purposes, during the pivoting motion, the front edge part positioned closest to the pivot axis is compressed less than the front edge part positioned the furthest from the pivoting movement. The end of the tip, which is positioned farther from the pivot axis and absorbs the maximal lever action, is consequently also put under a great deal of stress and, therefore, the danger that this end will abandon its alignment position produced by the first lever is additionally increased. Tips of a belt construction strip that are laterally curved away from the belt construction strip can be only partially aligned, with the limitations and risks explained. However, tips that are formed as curved axially inward toward the belt construction strip cannot be aligned via this method. Already the first lever arm either does not come into contact with the side edge or it is pivoted until it bends the tip further inward. The second lever arm then pivots inward and presses directly against the inwardly bent end of the tip and finally squeezes the end region of the tip. With curvatures of this kind, the danger of the original curvature being amplified further and possibly irreparably compressed cannot be prevented with a device according to U.S. Pat. No. 4,769,104.
The device according to U.S. Pat. No. 4,769,104 consequently permits a limited alignment of side edges in the region of the main part of a belt construction strip, and a limited ability to align the front edge of the belt construction strip. A particular, predetermined contour of the side edge and a tip of the belt construction strip cannot be adjusted by this system. It is also not possible in the alignment to take into account possible subsequent deformations to be expected after the alignment on the basis of empirical values by deliberate pre-deformations so that, with the occurrence of the subsequent deformations, these pre-deformations are compensated for by counteracting, previously adjusted deformations and produce a desired form.
The device contains a large number of individual mechanical parts having an independent mechanical device for aligning the front tip and a device for independently aligning the rear tip, as well as independent mechanical devices for processing the main part. The large number of lateral mechanical force effects, moreover, increase the danger that other undesirable deformations are produced by lateral friction contact with the belt construction strip.